Internal combustion engines often emit harmful oxides of nitrogen (“NOx”) during operation. Typically, the level of NOx formed increases as the peak combustion temperatures within a main combustion chamber increases. Therefore, lean fuel mixtures are often used to reduce the peak combustion temperatures in the main combustion chamber, and reduce the amount of harmful NOx emitted. A lean fuel mixture has a relatively large air-to-fuel ratio when compared to a stoichiometric air-to-fuel ratio. However, using a lean fuel mixture may result in incomplete combustion i.e. lean misfire within the main combustion chamber.
Pre-chamber spark plugs are known to create a conducive environment for igniting such lean fuel mixture. Ignition of the lean fuel mixture within the pre-chamber of the pre-chamber spark plug creates a jet of burning fuel that is further directed into the main combustion chamber. The jet further ignites the lean fuel mixture within the main combustion chamber to propagate ignited flame across the main combustion chamber. Generally, such pre-chamber spark plugs include two electrodes that define a predefined gap therebetween. This predefined gap is defined such that a spark is generated therein during compression stroke to ignite the fuel mixture. However, due to continual usage of the spark plug, the electrodes may experience wear and tear thereby increasing the gap.
U.S. Pat. No. 6,013,973 relates to a spark plug for use in conventional fuel ignition systems includes a housing and a ground electrode attached to the housing. A center electrode is located within the housing and is spaced apart from the ground electrode to form an electrode gap. An insulation member electrically separates the center and ground electrodes. A sub-combustion chamber is further located on the spark plug and encloses the electrode gap. A plurality of holes is located within the walls of the sub-combustion chamber where both a fuel-air mixture and combustion gasses pass through.